| 研究実績の概要 |
The chemical reaction mechanisms for hexafluoroacetylacetone (hfacH) and acetylacetone (acacH) have be investigated with pure and oxidized Ni. From the investigated mechanisms, we found that molecules have F atoms are more stable on a NiO surface because the negatively charged F atoms repulse with O atoms in the NiO surface. As a result, they do not allow C atoms to interact with Ni atoms that can cause the decomposition of these molecules. Moreover, this repulsing force will decrease the needed energy (the used temperature) to volatilize the metal complex and H2O molecules that cause the etching of oxidized metals. On the other hand, if F atoms are replaced with H atoms, the positively charged H atoms may interact with the O atoms in the surface which cause the dissociation of these molecules.
In addition, I found that the decomposition state of hfacH, trifluoroacetylacetone (tfacH), and acacH are more stable on a pure metallic surface. There are a barrier energy, relatively small, which can be passed by increasing the surface temperature. These results confirm that there is a self-limiting step when the oxidized metal etched thermally by these molecules.
From these results we can announce that hfacH gas is the best gas for thermal ALE from the following gases: hfacH, tfacH, acacH, and formic acid (fa) gas.
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